Struct SetupPacket 

#[repr(C)]
pub struct SetupPacket {
    pub bmRequestType: u8,
    pub bRequest: u8,
    pub wValue: u16,
    pub wIndex: u16,
    pub wLength: u16,
}

A SETUP packet as transmitted on control endpoints.

All transactions on control endpoints start with a SETUP packet of this format. (Some are then followed by IN or OUT data packets, but others are not).

The format of this packet (and the un-Rust-like names of its fields) are defined in the USB 2.0 specification, section 9.3. Other sections of the USB specification, and of the specifications of particular device classes, dictate what to put in these fields.

Control transactions are performed using UsbBus::control_transfer().

For instance, here is how to read the MAC address of an AX88772 USB-to-Ethernet adaptor:

let mut data = [0u8; 6];
let rc = bus.control_transfer(
        &device,
        SetupPacket {
            bmRequestType: DEVICE_TO_HOST | VENDOR_REQUEST,
            bRequest: 0x13,
            wValue: 0,
            wIndex: 0,
            wLength: 6,
        },
        DataPhase::In(&mut data),
    )
    .await;

Here, the “Request Type” indicates a vendor-specific (AX88772-specific) request, and the “0x13” is taken from the AX88772 datasheet and is the code for “read MAC address”. And a MAC address is 6 bytes long, as seen in wLength.

Fields

bmRequestType: u8

The type and specific target of the request.

bRequest: u8

The particular request.

wValue: u16

A parameter to the request.

wIndex: u16

A second parameter to the request.

wLength: u16

The length of the subsequent IN or OUT data phase; can be zero if the setup packet itself contains all the required information.

Trait Implementations

impl Debug for SetupPacket

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Format for SetupPacket

fn format(&self, f: Formatter<'_>)

Writes the defmt representation of self to fmt.